Braking apparatus



Oct. 15, 1935. s. SCHNELL I 2,017,635

BRAKING APPARATUS Filed July 9, 1952 ll/Il Inventor STEVE SCHNELL Att'yQ Patented a. 15, 1935 UNlTED STATES BRAKING APPARATUS Steve Schneil, St. Louis, Mo., assignor to Wagner Electric Corporation, St. Louis, Mo.,,a. corporation of Delaware Application July 9,1932, Serial No. 621,590

21 Claims. (Cl. 188-48) 2 My invention relates to braking apparatus for vehicles, its general object being to produce a brake friction device that is stable, easily controllable and which, in operation, produces ap- 6 proximately uniform pressure distribution over the drum periphery, and may be caused to develop a high braking torque without tendency to wedge into or look to the drum. A more specific object of my invention is'to 10 provide an expansible friction element embracing the major portion of the periphery of the brake drum and circumferentially extending means forapplying radial pressure throughout' a substantial arc of the portion of the element 15 to the rear of its anchor during brake application, the friction element in its preferred form being of the band type but having a semi-rigid forward" portion, the radial pressure means co- .tion.

, Other objects will become apparent from" the following description of one embodiment of my invention taken in connection with ,the accompanying drawing in which Figure 1 is a side 35 elevation of a brake assembly (the drum being shown in section), disclosing my improved brake; Figure 2 is a cross sectional view of the anchor pin assembly taken on the line 2-4 of, Figure l; and Figures 3 and 4 are cross sectional views taken on the lines 33 and 44, respectively, of Figure l. v g Referring to the drawing, the numeral I indi cates the drum of the brake which is secured in the usual manner to a'wheel of thevehicle and is enclosed on its open side by the backing plate or support 2 secured to some fixed p'art oi the vehicle. The friction element comprises, a brake lining carrying band 3 extending over substantially the entire inner periphery of thedrum 9 and expansible into engagement with the drum by suitable means, such as the hydraulic mechanism 4. The ends of the band are biased to off position by the usual spring 5, the *ofi position clearance at one end being determined by the adjustable stop ii and the other end by a combined adjustable stop and anchor pin I.

The-band or shoe 3 is preferably of Tsec tion throughout the major portion of its length, comprising a. lining carrying flange 'ii and a rein- 50 forcing web, the web being omitted over a section of the band, as shown, thereby forming two wsmcfipart web portions 9 and Hi. The section of the baid'carrying thefweb portion 9 will hereafter be referred toss the fforward" section and 55 theremainder of the band as the "rear? settion,

operating with the relatively flexible rear porthe drum being considered as rotating in the direction of the arrow (Figure 1) when the vehicle is traveling in a forward direction. The omission of the reinforcing web fromthe major portion of the rear section of the band allows this portion to be, flexible for the purposes hereinafter described.

An-arcuatechannel-shaped lever H is pivoted at one of its ends to the anchor1 pin I and connected atits other end by means of a pivot pin 10 12 with the inner end of the web- 9, which inner end may be free from the flange as shown. The

webs of the channel are provided with flange portions i3 which engage the lining carrying flange 8 over the flexible portion of the rear sec-' 15 tion of the band. A pin it carried by the flange. 8 extends through the lever and is provided with a spring I5 on its outer, end for biasing the lever into engagement with the flange during 0115" position of the brake.\

The portion of the aiichor pin 1 upon which the lever ii is pivoted, is eccentric to the main body of the pin in order to provide means for adjusting the lever with respect to the drum and also the off position of the end of the band. The anchor pin has bearing in the backing plate and is held in adjusted position by means of a nut i5 which clamps an integral shoulder i1 against the backing plate. A washer l8 cooperates with a groove on the end of the eccentric portion of 3 the pin to hold the lever in position.

An eccentric adjustable stop I9 cooperates with a projection 20 on the inner end of the web 9 to prevent the lever from swinging inwardly when the band is engaged and the drum is rotat- 3 ing in a reverse direction The stop'is positioned to lie substantially on an arc struck with a radius equal to the distance between the anchor pin 1 and the pin l2 and having a center at pin 1. The stop contacting surface of the projection 20 lies 40 upon an arc struck from the axis of pin l2, thus permitting the forward section of the. band to band withgthe drum is low since small force is required to bend the flexible portion of the band to the extent necessary for this purpose. As-' suming forward rotation of the drum, when the band is initially engaged with the drum, it 56 will have a slight circumferential movement with the drum which will cause the forward section of the band to act on the end of the lever ll, thereby swinging the lever outwardly toward the 6 drum and about the pivot pin l. The outward movement of the lever applies radial pressure distributed over substantially the entire flexible portion of the rear section of the band and the total braking pressure on this portion consists of this 10 radial pressure and the pressure applied by the hydraulic actuator 4. When the lever ll comes into action, the effective. anchor of the brake is at pivot pin l2 although the braking reaction is taken bythe pivot pin 1.

Since the drum tends to drag the flexible rear section with it, a pull is created which is transferred to the heel of the relatively rigid forward section,- causing the forward section to be swung outwardly about the pivot [2. The total braking pressure of the forward section of the band, therefore, consists of the pressure from the actuator 4, the pressure caused by the wrapping effect of the forward section, and the pressure created by the pull of the flexible section.

The adjustability of the pivot pin 1 is a very important feature of my invention for by it 1 am able to vary the distribution of the lever pressure on the flexible portion of the band. ,I'hisdistribution of the lever, I am enabled to vary the braking torque of a selected brake assembly 35, in instances where this may be advisable, as for example, to secure the desired relation to the torque of another assembly on the same vehicle. Under reverse direction of the vehicle, when the brake is actuated the band is effectively an- 40 .chored at its center and has characteristics similar to an ordinary hand brake, except that the relatively rigid section comprising the reinforcing web 9 will have greater braking effect than if this portion were of the usual band type. It will be understood that a radial pressure .lever of the general type hereindescribed, may be employed to apply pressure to other portions and forms of brake friction elements than herein shown and that I do not desire that the scope the appended claims.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is':

1. In braking apparatus, the combination of a support, a brake drum; a brake band adapted to have its-ends expanded to engage it with. the drum, and a lever pivoted to the support adjacent one end of the bandand connected to the 60 bandat a point intermediate the pivot and the other end of the band, said lever being adapted to apply radial pressure to the band over a substan- 1 tial arc thereof. p i

2. In braking apparatus, the combination of 65,- a support, a brake drum, a brake band adapted to have its ends expanded to engage it with the drum, and anchor means for said band, said anchor means comprising-a member pivoted to the support and connected to an intermediate 70 portionof the band, the intermediate part of the anchor member being adapted to apply radial pressure to a substantial portion of the band.

3. p A brake comprising in combination, a brake drum, an expansible brake band within the 75 drum, an anchor pin, and an arcuate member pivoted to the anchor pin and connected to the band at a point circumferentially spaced from the anchor pin, said arcuate member extending ,over and in contact with a substantial arc of the band, and being actuated by means of its 5 said connection with the band to apply a radial pressure to the band when the band is applied to the drum.

4. In braking apparatus, the combination ofa brake drum, a friction member adapted to 1 with the drum.

j 5. A brake comprising-in combination, a brake 20 drum, an expansible brake band within the drum and comprising a relatively rigid section and a flexible section, and means limiting circumferential movement of the band and applying a radial pressure on a major portion of the flexible 25 section.

6. A brake comprising in combination, a brake drum, an expansible brake band within the drum and comprising a relatively rigid portion and a flexible portion, a member pivotally anchored 30,

and having an arcuate surface extending over and in pressure contact with the flexible portionof the hand during brake application.

7. A brake comprising in combination, a brake drum, an expansible brake band within the drum 35.

and comprising a relatively rigid portion and a flexible portion, and a member pivotally an- .chored at one of its ends and connected at its other end with the band, said member having an arcuate surface extending over and in pressure contact with the flexible portion of the and a lever in pressure contact with an arc of the flexible portion vof the band during brake application, said lever being provided with a fixed pivot atone end and connected at its other end to the band. r 9. In braking apparatus, the combination of a support, a brake drum, a brake band adapted .to-

have .its ends expanded into engagement with the drum, a substa'ntial portion of said band 111-] termediate its ends being more flexible than the remainder, and a lever pivoted at one of its ends to the support and connected at its other: end to ,an intermediate portion of the band, said lever being adapted to apply radial pressure to the flexm ible portion of the band.

10. In braking apparatus, the'combination of over a portion of the band intermediate its ends than over the remainder, and means for anchoring said band and applying an outward pressure on the portion of greatest flexibility, said means comprising a lever having one of its ends pivoted to the support and'it's other end connected to the" i band, its intermediate portion contacting with the portion of the band having the greater. flexibility.

11: In braking apparatus, the combination on;

brake drum, a friction member 'adaptedto em- 'll,

brace a. major portion of the drum circumference, said friction member comprising a substantially annular lining carrying flange and a reinforcing web extending over a portion of said flange, and a lever extending over a. major part of the portion of the flange not provided with the reinforcing web, said lever being pivotally supported at one end and being connected at its other end with the reinforcing web,

12. In braking apparatus, the combination of a support, a brake drum, a brake band adapted to engage the drum, said band comprising a substantially annular lining carrying flange and circumferentially spaced apart reinforcing web portions, and a lever pivoted at one of its ends to one of the web portions and at its other end to the support, said lever being adapted to apply radial iiressure to the iiange intermediate the web poricns.

13. In braking apparatus, the combination of a support, a brake drum, a brake band adapted to engage the drum, said band comprising a sub stantially annular lining carrying flange and circumferentially spaced apart reinforcing web portions, and a lever pivoted at one of its ends to one of the web portions and at its other end to the support at a point adjacent the other web portion and being in contact with the flange intermediate the web portions,

1 2. In braking apparatus, the combination of a brake drum, a brake member adapted to embrace the major portion of the drum friction surface,

said brake member comprising a relatively rigid section and a. flexible section, and means forming an anchor cooperating with the inner end of the brake band within the drum, means to expand the ends of the band, and a lever adjustably pivoted to the support adjacent one end of the band and connected to an intermediate portion of the band, the adjustable pivotof said lever forming an adjustable stop for the ofi" position of the adjacent end of the band.

16. In braking apparatus, the combination of a support, a brake drum, a. substantially annular brake band adapted to be expanded into engagement with the drum, a lever pivoted at one of its ends to the support and connected at its other end to an intermediate point'of the band, said lever being adapted to be forced into contact with the band when the drum is rotating in one direction, and stop means limiting inward movement of the end of the lever which is connected to the band when the drum is rotating in the other direction.

a 17. In braking apparatus, the combina'tion of a support, a brake drum, a brake band adapted to have its ends expanded to engage it with the 5 drum, a lever pivoted to the support adjacent one end of the band and connected to the band at a point intermediate the pivot and the other end of the band, said lever being adapted'to applyradial pressure over a substantial arc of the band, and yieldable means for biasing the lever into contact with the band 18. In braking apparatus, the combination of a brake drum, a friction member adapted to embrace the major portion of the drum friction sur-. face, a lever for applying radial pressure to the friction member over a substantial arc thereof when the member is applied to the drum, and adjustable means for varying the distribution of the pressure between the friction member and drum 20' applied by said lever, I

I 19. In braking apparatuathe combination of a brake drum, a friction member adapted to embrace the major portion of the drum friction sur face, a lever supported at one end and connected as to the friction member to be actuated thereby, said lever being adapted to apply radial pressure 7 to the friction member over a substantial arc ,thereoi when said friction member is applied to the drum, the connection between said lever and friction device through which the lever is actuated being circumferentially displaced from the supported end of the" lever,

2%. In braking apparatus, the combination/of a support, a brake drum, a friction device adapted .to have its ends expanded'to engage itwith the drum, and anchor means for said friction device, said anchor means comprising a member carried by the support and connected to an intermediate portion of the friction device, an intermediatepart of said member being provided with an armate surface adapted to contact and apply radial pressure to. a substantial are of said friction device when it is engaged with the drum.

21. In braking apparatus, the combination of a support, a brake drum, a friction device adapted to have its ends expanded to engage it with the drum, and a member having aportion anchoring on the support" and another portion secured to the band, said membernbeing provided with an arcuate surface the curvature of which is substantially the same as that of the internal surface of the frictional device and said member contacting asubstantial portion of the friction device and applying a radial pressure thereto when the fric- 55 tion device is engaged with the drum.

STEVE SCHNELL. 

